Drain structure



J. E. EMBERSON DRAIN STRUCTURE June 3, 1969 Sheet Z 012 Filed Dec. 27.1965 JOHN E. EMBERSONI mrorneg June 3, 1969 J, E. EMBERSON DRAINSTRUCTURE Sheet Filed Dec. 27. 1965 INVENTOR JOHN E. EMBERSON I AfiornggUnited States Patent 3,447,329 DRAIN STRUCTURE John E. Emberson,Scarborough, Ontario, Canada, assignor to Wade International LimitedFiled Dec. 27, 1965, Ser. No. 516,470 Claims priority, applicationCanada, Nov. 20, 1965, 945,828 Int. Cl. E03c 1/26 U.S. CI. 61-63 1 ClaimABSTRACT OF TIHI DISCLOSURE A drain head has a removable plate whichcontains a notch, the sides of which converge together and are shapedalong their length in the form on one half of a parabola bisectedthrough its focus.

This invention relates to a drain structure and has particular referenceto a drain structure for controlling the rate of flow of water from aflat roof area into the downpipe and hence to the storm sewer system.

'Drain construction on a flat roof in the past has usually comprised adrain body set into the roof, the lower end of which is connected to thedownpipe with the upper end sealed by a flashing clamp over which ispositioned a grid sized to prevent the entry of solids large enough tocause blockage. No attempt has been made to control the flow even thoughthere is a limit to the amount of water which the downpipes can handlebefore overloading occurs with the resultant backing up. A conventionalmethod of dealing with this problem is to provide more downpipes thanare generally necessary to deal with the average storm but sufiicient innumber to ensure that flooding will not result in the occasional heavystorm; it will be realised though that this method has a disadvantage ofincreasing the cost of installation of the building.

It is obvious that the downpipes could be more scientifically andeconomically arranged if a drain structure is employed which wouldautomatically regulate the supply of water to the downpipe irrespectiveof the nature of the storm.

Accordingly, it is one feature of the invention to provide a drainstructure in which the flow rate is directly proportional to the head ofwater; it is a further feature of the invention that such a drainstructure is adapted for incorporation into the flat roof drainconstruction hitherto employed.

The control of the flow rate through the drain head is accomplished byproviding one or more notches in the wall of the drain head, the lowerend of each notch being positioned just above roof level. The upwardlyextending sides of each notch converge towards each other and are shapedalong their length in the form of one half of a parabola bisectedthrough its focus. The flow through such notches referred to hereafteras parabolic is linearly related to the head of Water on the roof; allthe notches provide increasing resistance to the drainage of Water andthe delay in run off prevents over-loading of the downpipes and stormsewers.

It is a further feature of the drain head according to the inventionthat the parabolic notches are located in plates which form the sides ofa frame, the plates being adapted to be removably secured to the frame,the plates and the frames together forming the drain head. As a resultthe resistance to drainage of water from the roof may be adjusted byreplacing an existing plate with one having a dilferent sized notch.

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The invention will now be described with reference to the accompanyingdrawings, in which:

FIGURE 1 is a perspective and exploded view of a drain structureaccording to the invention;

FIGURE 2 is a view of the removable plate of a drain structure accordingto the invention;

FIGURE 3 is a perspective view of the underside of a drain structureaccording to the invention.

With reference to the accompanying drawings the drain structure includesa base 10 having a centrally disposed orifice 12 to provide a flange onwhich are positioned spaced apart integral upstanding lugs 14. Acentrally disposed aperture 16 is provided in each of the lugs 14, eachaperture 16 serving the purpose of accommodating a respective threadedmember 18, each of which extends upwards from an inwardly extending lug20 of a conventional roof drain body 22 set into the surface of theroof. The threaded members 18 normally serve to secure in place aflashing clamp 24, the threaded members 18 passing through notchedabutments 26, the flashing clamp 24 being secured in place by nuts andWashers 28. It is a particular advantage of the invention that thecontrolled drain structure described hereunder is adapted to beremovably secured to the conventional flashing clamp 24 and roof drainbody 22. Extending upwards integrally from the flange base 10 is a wall,generally denoted by the numeral 30, forming a frame which, in thepreferred embodiment, is substantially square and surrounding theorifice 12. However, it will be appreciated that the configuration ofthe wall 30 is not necessarily square, e.g. it may be circular.

The frame 30 is provided with opposed apertures 32. A removable plate 34closes each of the apertures 32; the plate 34 is secured to the frame 30by means of an abutment 36 which is secured to the underside of the base10 adjacent the orifice 12 by means of a screw 38, see FIGURE 2. Theplate 34 is locked in position by the interaction of opposed flanges 40hearing against the underside of the frame 30 and a tongue 42 whichbears against the outside of the frame 30.

It is a feature of the invention that one or more of the plates 34 isprovided with an inverted parabolic notch 44, the size of which isselected with respect to the average storm determined over a reasonableperiod of time and also relating to the maximum depth of water based onthe usual minimum design roof load rating. Generally the size of theparabolic notch 44 is determined on the basis of using a 3" design waterlevel which represents a roof load of approximately 15 lbs. per squarefoot which is only about half the usual minimum design roof load rating.Since there is a wide variation in rainfall depending on geographicconditions, it will be appreciated that in some cases each plate 34 willhave a parabolic notch 44 or else in areas where rainfall is limitedonly say one plate 34 is provided with a parabolic notch 44, the otherplates 34 being blank. The arrangement renders the flow rate directlyproportional to the depth of water on the roof with the result that itmakes accurate calculations and sizing of the downpipes possible, themaximum width of the parabolic notch 44 being at the bottom whichensures a minimum time for proper draining of the roof after the stormis over. Expressed in another way the arrangement may be such that theflow is below that of the rate previously found with a conventionalrating with the result that the sewer system is not overloaded but atthe same time the maximum level of water on the roof is kept within asafe limit which is approximately 50% of that for which the roof isdesigned.

In strict theory the lower edge of the parabolic notch 44 should extendoutwards and terminate at the junction of the opposed lower corners ofthe plate 34 where it joins the wall 30. However, with this constructionit is more difiicult to cast -the plate 34 since it will have a sharpcorner and also a portion would be provided which could easily breakaway from the remainder on handling. Accordingly, the lower end of theparabolic notch '44 is turned downwards as at 46 some distance removedfrom the adjacent lower corner of the plate 34. The area of theparabolic notch 44 thus eliminated by turning down the edge 46 iscompensated by deepening the base of the notch 44 in the plate 34thereby providing comparable flow.

The controlled drain structure according to the invention may be usedindependently of the conventional roof drain construction but where itis utilized to adapt the latter it is simply secured in place bysecuring the threaded members 18 in the orifices 12 and applying screwsand washers 48. A conventional grid, not shown, would then be positionedover the drain structure to limit the entry of solids which would causeblockage in the downpipe.

While certain embodiments have been illustrated and ated that theinvention is not limited thereto, but contemplates such modificationsand other embodiments as may be utilized without departing from theinvention.

I claim:

1. A drain head secured to a surface area for removing water therefrom,said head including an upstanding wall and a notch in said wall, thelower end of said notch being just above said surface area and theupwardly extending sides of said notch converging towards each other,said sides being shaped along their length in the form of one half of aparabola bisected through its focus; said upstanding wall beingremovably secured to a frame and said frame being secured to saidsurface area.

References Cited UNITED STATES PATENTS 810,879 1/1906 Perry 61-103,158,171 11/1964 Eckert 137262 3,246,582 4/1966 Wade et al. 9433REINALDO P. MACHA-DO, Primary Examiner.

J. K. BELL, Assistant Examiner.

